When an automotive motor will not start or runs irratically, the first item an auto mechanic looks to is the ignition system. Of primary importance to the operation of an ignition system is the spark to the spark plugs or ignitors. Invariably a mechanic will check the spark when testing an ignition system.
In the past, automotive spark has been tested by removing the spark plug holding the plug against the engine to complete the spark plug circuit while the engine is cranking, and observing the presence and quality of a spark across the plug electrode gap. A second method has been to remove a spark plug wire from a spark plug and to hold this wire in close proximity to the engine block while the engine is cranking to observe the presence and quality of a spark between the end of the wire and the engine block. Both of these methods utilize a rather make-shift procedure to perform the test. Moreover, both procedures subject the mechanic to a shock hazard. Very often, auto mechanics who almost never wear electrically insulated gloves when working on automobilies, will receive a shock either through the insulation surrounding the spark plug wire or from coming in contact with metal portions of a spark plug or by coming in contact with a conductive portion of the spark plug wire. Electrical agitation "shock" received through spark plug insulation is uncomfortable and annoying to the mechanic. Electrical shock received directly from a conductor in contact with the conductive portion of the spark plug wire can cause excessive discomfort and even create a severe health hazard to the mechanic.
In addition to the health hazard, the make-shift tests described above provide a imprecise way of observing the spark. It is well known that the true evaluation of ignition spark is only obtained under realistic spark conditions. This means that the spark gap should be of a predetermined fixed distance and in a position where the mechanic can readily observe it. The make-shift holding of the spark plug against the engine block or the holding of the spark plug wire in close proximity to the engine block where there is a subjective and imprecise distance between the end of the wire and the engine block are rather unsatisfactory methods of testing ignition spark. Moreover, a good ground is not always established. A poor ground will alter the condition of the spark.
The testing of the quality of ignition spark becomes more important with the advent of electronic ignition systems. These electronic ignition systems provide high performance and exacting standards of operation for ignition of automotive motors. No prior art devices are known to be directed precisely to the structure and operation of an ignition spark indicator apparatus.
What is desired therefore, is a spark indicator apparatus which provides a safe alternative to the mechanic disconnecting a spark plug wire and holding it in close proximity to the engine block. Moreover, such an indicator must signal the presence and quality of a spark adequately for a mechanic to make an analysis under the relatively noisy and relatively darkened working conditions found typically in automotive repair shops.
An object of this invention is to provide an apparatus specifically designed for the determination of the presence of an automotive ignition spark.
Another object of this invention is to provide such a spark indicator which indicator provides a visual and audio indication of the spark.
A further object of this invention is to provide such a spark indicator apparatus having its outer surfaces completely enclosed and insulated for protecting the auto mechanic handling the apparatus from electrical shock hazard.
A further object of this invention is to provide such a spark indicator apparatus having a precise and predetermined spark gap for permitting a spark of predetermined length.
An even further object of this invention is to provide such a spark indicator apparatus having connectors for establishing good ground and ignition current connections.